<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
  <p>A paragraph with a <button>button</button>.</p>
  <script>
    let para = document.querySelector("p");
    let button = document.querySelector("button");
    para.addEventListener("mousedown", () => {
      console.log("Handler for paragraph.");
    });
    button.addEventListener("mousedown", event => {
      console.log("Handler for button.");
      if (event.button == 2) event.stopPropagation();
    });
  </script>
</body>
</html>